In recent years, Echinacea has become one of the most popular commercial medicinal herbs in the world (Wills and Stuart, Alkylamide and Cichoric Acid Levels in Echinacea purpurea Grown in Australia, Food Chemistry, 67, 385-388 (1999)). Echinacea has received international attention because of its immunostimulatory and other beneficial effects. Although several phytochemicals in Echinacea work together in providing these beneficial effects, caffeic acid derivatives, most notably cichoric acid, and lipophilic alkylamides are indicated as making considerable contributions to Echinaces's immunostimulatory activity (Bauer, R. and Wagner, H., Echinacea Species as Potential Immunostimulatory Drugs, Econ. Medic. Plant Res., 5, 253-321, Wagner, H. and Farnsworth, N. R. (Editors), Academic Press Ltd., New York, N.Y. (1991)).
Echinacea is the genus name for nine herbaceous perennial species native to North America. Echinacea, however, usually refers to Echinacea angustifolia, Echinacea purpurea, or Echinacea pallida. Echinacea was first widely used by several North American Indian tribes against various conditions such as wounds, burns, insect bites, headaches, stomach cramps, coughs, and the measles. The primary use of Echinacea is for increasing resistance to infections in the upper respiratory tract and colds in the upper respiratory tract (Bauer, R. and Wagner, H., Echinacea Species as Potential Immunostimulatory Drugs, Econ. Medic. Plant Res., 5, 253-321, Wagner, H. and Farnsworth, N. R. (Editors), Academic Press Ltd., New York, N.Y. (1991)). Echinacea has anti-inflammatory and antibacterial activities useful in treating conditions such as skin inflammations and urinary tract infections. It has been indicated that Echinacea also fights cancer by stimulation of key lymphocye production, which triggers natural killer cells to destroy tumor cells (see Lersch, C. et al., Nonspecific Immunostimulation with Low Doses of Cyclophosphamide, Thymostimulin, and Echinacea purpurea extracts (Echinacin) in Patients with Far Advanced Colorectal Cancer, Cancer Invest. 10(5): 343-348 (1992)).
Cichoric acid, which is a caffeic acid derivative, and tetraene alkylamides are two types of phytochemicals present in Echinacea that are thought to be primarily responsible for Echinacea's beneficial activity. Cichoric acid, in particular, has been noted to inhibit HIV-1 integrase and replication in tissue culture (Robinson, W. et. al., Inhibitor of HIV-1 Replication that Inhibit HIV Integrase, Proc. Natl. Acad. Sci. USA, 93, 6326-6331 (1996)).
The chemical structure of cichoric acid and tetraene alkylamides are shown below: ##STR1##
Other non-limiting examples of caffeic acid derivatives are echinacoside, verbascoside, chlorogenic acid, isocholorogenic acids, cynarine, and caftaric acid, as shown below.
##STR2## R.sub.1 R.sub.2 R.sub.3 R.sub.4 R.sub.5 R.sub.6 2-O-Caffeoyl-tartaric acid (Caftaric acid) H H OH H -- -- 2,3-O(Di-caffeoyl-tartaric acid (Cichoric acid) H R' OH H OH H 2,3-O-Di-caffeoyl-tartaric acid-methylester CH.sub.3 R' OH H OH H 2-O-Feruloyl-tartaric acid H H OCH.sub.3 H -- -- 2-O-Caffeoyl-3-O-coumaroyl-tartaric acid H R' H H H H 2-O-Caffeoyl-3-O-teruloyl-tartaric acid H R' OH H OCH.sub.3 H 2,3-O-Di(5-[.alpha.-carboxy-.beta.-(3,4-di-hydroxy-phenyl)-ethyl)- H R' OH R' OH R' caffeoyl]-tartaric acid 2-O-Caffeoyl-3-O-(5-[.alpha.-carboxy-.beta.-(3,4-dihydroxy-phenyl)- H R' OH H OH R' ethyl)-caffeoyl]-tartaric acid ##STR3## R R' Echinacoside Gluocse (1,8-) Rhamnose (1,3-) 6-O-Caffeoyl-echinacoside 6-O-Caffeoyl-glucose (1,6-) Rhamnose (1,3-) Verbascoside H Rhamnose (1,3-) Dirhamnosyl-verbascoside H H ##STR4## R.sub.1 R.sub.2 R.sub.3 R.sub.4 3-O-Caffeoyl-quinic acid (Chlorogenic acid) H R H H Isochlorogenic acids H R R H H R H R H H R R Cynarine R H H R ##STR5## ##STR6## ##STR7##
Other non-limiting examples of alkylamides in the roots of E. purpurea and E. angustifolia are shown below: ##STR8## ##STR9##
It is believed that the root portions of E. purpurea provide the highest concentration of alkylamides. The concentration of caffeic acid derivatives are believed to be similar in root and aerial samples. Nonetheless, the concentrations of caffeic acid derivatives and alkylamides may vary from one species of Echinacea to another and may also vary within the same species. The variation of caffeic acid derivatives and alkylamides concentrations within the same species are believed to be partly due to environmental factors, such as the difference in daylight and seasonal change in rainfall.
In the past, to obtain increased amounts of caffeic acid derivatives and alkylamides, one had to grow and harvest more Echinacea plants. Thus, the number of plants having caffeic acid derivatives and alkylamides determined the amount of these phytochemicals available for use in dietary supplements or in other compositions. As a result, more money, time, and effort were involved in producing a commercial product containing these phytochemicals. Therefore, there remains a need to provide a method of increasing the concentrations of caffeic acid derivatives and alkylamides per gram of plant material or, alternatively, a method of making a raw plant material that has increased concentrations of these phytochemicals per gram of plant material. There also remains a need for a composition having increased concentrations of caffeic acid derivatives, such as cichoric acid, and alkylamides, such as tetraene alkylamides, in dietary supplements because of their immunostimulatory and other beneficial effects. The present invention meets the foregoing needs by providing a simple, cost effective method of increasing the concentrations of caffeic acid derivatives (i.e. cichoric acid) and alkylamides (i.e. tetraene alkylamides) in Echinacea and other plants having these phytochemicals as well as compositions containing the same.